It is known in the prior art to arrange and mount flap devices in air intake port systems of combustion engines, wherein various kinds of flap devices function in different ways. In other words, flap devices can serve, in a known manner, as switch-over flaps to switch over the effective length of the intake port pipe of an air intake port system, or as tumble flaps or swirl flaps for producing a swirl in the cylinder head of an air intake port system.
In German Document DE 199 44 623 A1, an air intake port system is disclosed in which a swirl flap device is inserted into an insert duct in the air intake port system. The swirl flaps are arranged in an insert piece that is formed by two insert halves placed together. These insert halves are joined together, and via bearing holes support the swirl flap so that the swirl flap is held in place. The entire swirl flap device can then be pushed into a lower part of the housing of the air intake port system and mounted there by using screws.
In German Document DE 196 14 474, an air intake port system is disclosed in which a switch-over flap shaft carries several switch-over flap bodies, wherein the shaft is supported via two-component bearing mating parts. The switch-over flap shaft is placed into the bearing mating parts and the bearing mating parts are pushed into corresponding receiving apertures in the housing of the air intake port system. The switch-over flap device, or the bearing mating parts, are prevented from falling out of place by placing a second housing part of the air intake port system on top of the bearing mating parts. In this manner, the bearing mating parts are gripped from all sides by the housing of the air intake port system. As a result of this construction, a bearing mating part is arranged on both sides of each switch-over flap.
In German Document DE 199 46 861, an air intake port system with a tumble flap device is disclosed that includes a one-piece bearing frame with multiple tumble flaps arranged therein. A number of positioning elements, which are not shown in more detail, are embodied as mating pins and are provided for mounting the bearing frame on the housing of the air intake port system. In this way, a positive engagement connection is made between the bearing frame of the tumble flap device and the housing of the air intake port system, whereby the entire flap device is not prevented from falling out, in the direction of the cylinder head, until the air intake port system is screwed onto the cylinder head.
In German Document DE 101 43 384, an air intake port system with a switch-over flap device is described that includes an insert frame and a pivoted switch-over shaft inserted therein. The reference teaches a one-piece bearing frame that accepts two switch-over flap shafts for a V engine. Here too, the entire insert frame is inserted into corresponding recesses formed in the housing of the air intake port system and is then fixed in the air intake port system by placing the two housing parts together.
Finally, in German Document DE 102 36 393, a tumble flap device for an air intake port system is disclosed wherein an individual bearing element is assigned to each flap. Each tumble flap can be tilted in its respective bearing element. These bearing elements, as taught by German Document DE 102 36 393, are also placed first with the flaps in positive engagement in a first housing part of the air intake port system and are then fixed in place by screwing on a second housing part.
However, to fix a flap by placing two housing parts, one on top of another, requires that the respective flap device be arranged to coincide to where the housing is also divisible at this point. In many cases, however, it is not possible to arrange the flap devices so as to be disposed at a divisible point of a multi-part housing. In these instances, a different mounting must be selected such as by employing screwing, for example. Unfortunately, such a mounting structure, provided with additional mounting means utilizing a frictional connection, leads to a larger number of components. Having to employ a larger number of components results in the additional disadvantage that vibrations from the engine can cause loosening of the mounting means, which can lead to a damaging of the engine as well as interruption in engine function.
On the other hand, a mounting constructed by placing two housing parts, one on top of another, establishes narrow degrees of tolerance that must be strictly adhered to during the manufacture of the corresponding bearing surfaces. Such strict adherence to the narrow degrees of tolerance leads to higher manufacturing costs. Strict adherence to narrow degrees of tolerance is particularly difficult when injection-molded plastic shafts are used, especially those produced in one piece structures incorporating the flaps and also additional stops, where possible. As a rule, this kind of injection-molding leads to the shaft becoming deformed, and such deformation must be compensated for by an exact and fixed arrangement of the bearing elements.
In accordance with the problems encountered in the prior art mountings, an object of the present invention is to create a mounting for a flap device in an air intake port system that successfully mounts the flap device, even at positions in the air intake port system where it is generally not possible to employ the housing components of the air intake port system to positively engage and fix the flap device without using additional mounting means. It is another object, in accordance with the present invention, to achieve an exact fixing of the position of the bearing elements in the housing without having to adhere to narrow tolerances so that cost-effective injection-molded plastic shafts can be used in the construction of an air intake port system. In accordance with the present invention, another object is to provide a flap bearing mounting on an air intake port system that, when compared with mountings employing screws or the like, achieves greater safety and a longer service life.